British aid to Rwanda is under threat because of "credible and compelling
evidence" of its support for rebels in the Democratic Republic of
Congo, ministers have warned.

Fresh details of Rwanda's backing for the M23 movement were published in a final report to the United Nations Security Council that also accused Uganda of helping the rebels in Congo.

In a joint statement, William Hague, the foreign secretary, and Justine Greening, the international development secretary, they said: "We judge the overall body of evidence of Rwandan involvement with M23 … to be credible and compelling.

"We will be studying the implications of this report in full, but these allegations will necessarily be a key factor in future aid decisions to the Government of Rwanda."

On Thursday night, Prime Minister David Cameron urged Paul Kagame, the president of Rwanda, to pressure the rebels to withdraw from the Congolese city of Goma.

Mr Cameron, who was attending a European Union summit in Brussels, also pressed Mr Kagame to prove that M23 had no links to the Rwandan government.

Britain has already committed to giving £75 million to Rwanda this year. Another £21 million was due to be delivered next month.

It joined other European nations and the US in suspending donor payments to the government of Paul Kagame, Rwanda's president, after the UN report's initial findings were leaked in July.

But Andrew Mitchell, the former International Development Secretary, drew intense criticism when he reinstated £16 million of aid on his last day in office at DfID.

Mr Hague and Miss Greening called Rwandan and Ugandan support for the M23, "unacceptable, damaging to the security of the region, and in direct contravention" of Security Council resolutions.

The M23 was "a creation" of Rwanda, said Steven Hege, coordinator of the "Group of Experts" mandated to investigate breaches of international arms embargoes in Congo, which wrote the report to the UN.

The government of Rwanda sent weapons, ammunition and uniforms to Bosco "The Terminator" Ntaganda, the titular head of the movement, and helped to smuggle the supplies into Congo.

Two units of Rwandan soldiers have been permanently based in eastern Congo since before the M23 was formed in April, and its special forces fought alongside the rebels in clashes in Rutshuru in July, the report continued.

James Kabarebe, Rwanda's defence minister, was ultimately in charge of the rebels, giving orders to their commanders and funding recruitment drives to boost their ranks.

The investigation's final publication came as fresh fighting erupted on Thursday around Goma, the provincial capital of eastern Congo that has been in rebel hands since Tuesday.

Mortars and small arms fire were heard in the town of Sake, 20 miles northeast of Goma. There were reports that Congolese government troops had begun a counter-offensive.

Joseph Kabila, Congo's president, has promised to study the rebels' grievances, but said a precondition for the start of talks was that they pulled out of Goma.

Jean-Marie Runiga, the head of the M23's political arm, rejected that. "We'll stay in Goma waiting for negotiations," he said. A spokesman for the M23 meanwhile told AFP, France's national news agency, that Mr Runiga was on his way to Uganda for discussions with President Museveni.